It's largely been said, but I cannot fathom how a company could expect someone to fly Y LHR-JNB, attend a days meetings/workshops with a client, and then fly back Y JNB-LHR that night, and go to work the next day.

It would have to be J to ensure that you get a good length sleep, ability to put nicely kept suit on (shower at LHR, sadly not JNB) etc.

Best argument for me is definitely value of time and wasting 2 days each way is far more expensive than the flight cost. Second best argument is attrition - you wouldn't keep anyone if they were having to do that every few weeks in Y!